Google Realtime was designed to pull real-time social networking posts as well as tweets into Google's search results. When there was a big new event, for example, Google Search would display tweets and social posts on the topic, giving the search more social relevance.

However, last summer Google noted in a tweet said it was exploring how to incorporate its new social network, Google+, into the service.

The day before Google's Realtime Search was taken down, Google's deal to access Twitter 's stream of tweets ran out. And today, unlike search rival Microsoft Bing , Google no long can use Twitter's traffic flow.

Now it appears there's a major bump in the road in terms of getting Twitter back in the deal.

"Anytime you are negotiating with a company, it's true that the devil's in the details," Costolo said. "We just can't agree on what the appropriate value exchange is. And I'm not just talking dollars."

Costolo was quick to add that he hasn't given up on the possibility that the two companies can find common ground on the issue. "We talk to these guys all the time, so we'll see what happens," he said.

Google, meanwhile, has not given up on Realtime search.

Last week, Vic Gundotra, a senior vice president of engineering at Google, reported in a Google+ post that the company was rolling out real-time search results for its new social network.

"Now when you search in Google+, you'll see a message about new posts the instant they're available," wrote Gundotra. "If you click on this message, or select "most recent, then relevant posts will start appearing in real time."

Smart home- or wearable tech: which is more likely to benefit your digital life this year?

I'm more likely to buy smart home- than wearable tech this yearI'm more likely to buy wearable- than smart home tech this yearI'll probably buy both smart home- and wearable tech this yearI'm unlikely to buy smart home- or wearable tech this yearNot sure/don't know